In a valve connecting the fuel tank and a vent passage, there is a valve forming a support portion of a cantilever float valve body by a sift formed in a bottom portion of a housing forming the valve, and absorbing impact energy when the float valve body descends by bending of the support portion (see Patent Documents 1 and 2).
In this kind of valve, it is required to reduce a site as small as possible from various demands. Therefore, there is also a limit in forming the support portion in the bottom portion of the housing. However, in the valve of the Patent Document 1, the slit is formed in a radial direction from a center of the bottom portion of the housing (see FIG. 2 of the Patent Document 1), and reduction of a diameter of the valve immediately results in a shortening of a whole length of such support portion. As the whole length of such support portion becomes shorter, bending of the support portion becomes harder, so that in order to effectively absorb the aforementioned impact energy, it is necessary to ensure that the whole length of such support portion be as large as possible even if the valve is reduced in size. On the other hand, in the Patent Document 2, the slit is formed in parallel with a tangent of a circle of the housing having a circular shape in a cross section (see FIG. 2A in of the Patent Document 2), and the reduction of the diameter of the valve does not immediately result in the shortening of the whole length of such support portion; however, the whole length of the support portion cannot be ensured at a maximum.